A contaminated area is defined as an area that, because of human activity, has a level of harmful substances that causes either damage or a significant risk to the environment or to health, or loss of habitability, or that creates a comparable disadvantage.
Contaminants may reach the soil as a consequence of accidents or other incidents, of numerous types, or in the form of smaller, gradual emissions over a long span of time. Sometimes the cause may be a historic habit of burying waste.
Through the soil, substances may spread to groundwater, waterways, or surrounding areas. Their impact on the environment and on health may not be detected until decades after the operations in question have ceased.
Risk management
If an area is deemed to be contaminated, actions must be taken to reduce the hazards and risks to an acceptable level. Acceptability is determined on the basis of the purpose of use of the land. In practice, the authorities issue a notification or environmental permit decision that specifies the minimum targets for the remediation of the land.
Risk management may be carried out by removing harmful substances, reducing their spreading, or limiting exposure to the substances (for instance, through land-use planning).
The general principle behind the Finnish Environmental Protection Act (1096/1996) is that the environmental impact of harmful substances should be prevented or, if this is impossible, limited as much as possible. Finnish laws and decrees also contain requirements related to assessment of land contamination and to clean-up needs, the assignment of clean-up obligations, permits related to remediation, and the obligation to provide information when selling or renting out property.
Licensing and supervisory authorities
The licensing and supervisory authorities operating in Finland within the ambit of land-contamination control are the regional Centres for Economic Development, Transport and the Environment; the municipal environment institutes operating in Helsinki and Turku; and (for environmental permits) the regional state administration agencies.
Soil condition database
The Finnish environmental administration created the MATTI soil condition database for management of site-specific data related to land contamination. It contains information on land areas that are potentially contaminated, confirmed as contaminated, cleaned up, and confirmed as clean. The database can be accessed by environmental, land-use, and building-supervision authorities. Property owners can check and update information pertaining to their real estate. Property-specific reports may be requested from regional Centres for Economic Development, Transport and the Environment, while questions related to bigger areas are answered by the Finnish Environment Institute (SYKE).